Power press with a flywheel and spindle drive

ABSTRACT

A power forging press in which a press stand is provided with a drive having a flywheel, a spindle and a drive device, and a workpiece support. A ram is mounted for relative movement with respect to the workpiece support and a wedge is housed in the press stand and acts on the ram, with the flywheel-spindle drive being arranged with the axis of the flywheel and its spindle extending transversely to the direction of movement of the ram, the spindle and wedge being operably connected.

United States Patent 1191 1111 3,874,218 Bachmann Apr. 1, 1975 [54]POWER PRESS WITH A FLYWHEEL AND 2,245,573 6/1941 Criley 72/454 SPINDLEDRIVE 3,122,033 2/1964 Riemenschneider 3,139,816 7/1964 JemisonInventor: Horst Bachmann, i g Germany 3,512,476 5/1970 Georg 100/270[73] Assignee: Langensteinszschemann 3,595,163 7/1971 Baumann 100/270Aktiengesellschaft, Coburg, FOREIGN PATENTS OR APPLICATIONS Germany1,023,549 12/1952 France l0O/29l 7,550 0/1838 United Kingdom 100/291[22] 1973 85,091 12/1935 Sweden.l 100/291 [21] Appl. No.: 392,487

[63] gganntfjrgtilzgciion of Ser. No. 116,507, Feb. 18, 1971, Attorney,Agent or Firm HOHman & Stem [30] Foreign Application Priority Data [57]ABSTRACT Feb. 19, 1970 Germany 2007505 A P forging Press in which aPress Stand is P vided with a drive having a flywheel, a spindle and a52 us. c1 ..72/4s2,72/454,100/2s9, drive device, and a workpiece SupportA ram is loo/291 mounted for relative movement with respect to the 51Int. Cl. 3B21j 9/18 workpiece pp and a Wedge is housed in the Press [58]Field 01 Search 72/452, 453, 454, 443, Stand and acts the With theflywheel-Spindle 7 5 00 7 3 7 drive being arranged with the axis of theflywheel and 289 290 291 its spindle extending transversely to thedirection of 5 References Cited movement of the ram, the spindle andWedge being UNITED STATES PATENTS Operably Conmcted- 827,833 8/1906 Webb100/291 10 Claims, 5 w g gures L3 I I, 1 1 /'5g PATENTEMPR' 11ers3.874.218

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POWER PRESS WITH A FLYWHEEL AND SPINDLE DRIVE BACKGROUND OF THEINVENTION This invention relates to a power press with a die block and aflywheel and drive for a ram adapted for up and down movement, with thedrive having spindles.

PRIOR ART A key press is disclosed besides spindle presses by the GermanPatent Specification No. 1,265,548. In the case of the known wedgepresses, a crank drive actuates a wedge gear unit which in turn acts onthe ram. In addition, wedge presses are possible in which the wedge gearunit is actuated by a hydraulic cylinderand-piston drive.

Power presses of the type defined at the outset are known from theGerman Patent Specification No. 292,206 or from the German lain opendocument No. l,283,972. They possess either a stationary or an axiallymovable, vertically arranged spindle. The flywheel is either rigidlyconnected to the spindle or there is a clutch between spindle andflywheel, in which the spindle either engages at the ram with its threador is rigidly connected to the ram. The power presses operate eitherwith only one individual flywheel or with two flywheels which can becoupled together, the fixed flywheel being rigidly connected to thespindle and the loose flywheel being free of the spindle, but beingcapable of being connected to the spindle. These power presses possess,with a determined flywheel mass of the flywheel, a determined spindlerotation and a determined spring rigidly of the press body, acorresponding stress on the spindle. The fixed spindle arrangement witha vertical spindle has, in addition, the disadvantage that in thespindle portion between the spindle screw and traverse mounting thereoccurs, in a superimposed manner, pressure and torsion stresses. Thespindles must be made larger to correspond to this superimposed stress.This is not only expensive but also gives rise to a relatively largefrictional moment in the spindle nut.

As is well known, the drive of the hitherto known spindle presses withan electric motor connected direetly to the spindle has the disadvantagethat the power supply is loaded non-uniformly with short current surges.The energy of the press and the losses arising from the acceleration ofthe flywheel have to be supplied in the short acceleration time by thepower supply. Particularly in the case of fast striking power presses.the instantaneous power is very large in relation to the mean power.These relationships are undesired and become all the more problematicthe greater the spindle press is made.

OBJECTS AND SUMMARY OF THE INVENTION One object of the invention is toprovide a power press of the type defined at the outset which, with animproved flywheel mass and improved spindle rotation has improvedspindle stress.

The present invention provides a power forging press comprising a pressstand provided with a drive having a flywheel, a spindle and a drivedevice, a workpiece support, a ram mounted for relative movement withrespect to the workpiece support, and a wedge housed in the press standand acting on the ram, with said flywheel-spindle drive being arrangedwith the axis of the flywheel and the spindle extending transversely tothe direction of movement of the ram, and means operably connecting thespindle and wedge.

In this power press, there is a step-down gearing viz a wedge gear unitconnected between the energy storage wedge system (flywheel) and theram. The spindle stress is reduced by the stepping down of the wedgegear unit approximately in the ratio of the stepping down, with thespindle rotation becoming inversely proportional thereto. The flywheelmasses, in turn, are reduced inversely proportionally by the square. Thedisadvantage, described at the outset, of a vertical, stationarilyarranged spindle is eliminated by the transverse mounting of thespindle. The flywheel is arranged on the side of the spindle free fromcompressive stress, so that the spindle portion between the flywheel andspindle nut is stressed substantially only by torsion stresses and theother part between the nut and the thrust bearing essentially only bycompressive stress.

A switchable friction or slipping clutch may be provided between thespindle and the flywheel. The clutch serves as an overload protection,i.e., it prevents stressing of the power press component parts by aninadmissably large force. The switchable slipping clutch may be embodiedin a switchable manner in such a way that shortly after the beginning ofthe slip, the friction surfaces are completely separated from each otherand remain separated during the return motion.

The loose flywheel is not negatively loaded during the return motionofthe ram to the upper starting postion, resulting in that a smallamount of flywheel energy has to be overcome. The loose flywheel can,during the return motion, remain stationary or be loaded in the positivedirection so that on a new work stroke a part of the energy is alreadyavailable.

It is, however. in practice very expensive to make large clutches ofthis type with extra-ordinary high moments of rotation as switchclutches. By the interposition of a step-down gear, the slip moment ofthe clutch is reduced proportionally to the step-down ratio, e.g., inthe case of a stepdown ratio of i=2, by half. In this way, it ispossible to uncouple the flywheel at the beginning of the slipping andto keep it separated from the spindle during the return motion.

In a relatively small spindle press, the clutch is disengaged onattaining the so-called slipping moment or in the lower dead point inthe manner described above, i.e., the electric motor is fully loadedduring the forward motion only, while during the return motion it isoperated with about half load. In this way, the motor is substantiallythermally relieved of load and the degree of efficiency is improved. Ina [larger spindle press, the flywheel is disengaged in the same mannerduring the return motion. Furthermore, the disengaged flywheel iscontinuously driven in an unaltered direction of rotation during thereturn motion by a second electric motor which can be substantiallysmaller than the first.

If the striking sequence is not directly consecutive, the motor canbring the flywheel to the synchronous rotation before the next workingcycle is started. The motor, therefore, normally runs withoutinterruption as long as the press is in operation. It is also possibleto disconnect the motor shortly before the impact and switch it on againonly after the impact. During the pressing operation, the motor isretarded by the flywheel masses, but after the disengagement of theflywheel, it is immediately accelerated once more by the motor. Duringthe forward motion, both motors together accelerate the flywheel massescoupled together. By this measure not only is the effective degree ofdrive decisively improved but also the abovementioned unfavorable powersupply loading is eliminated by the removal of the high current peak andidle power.

The starting current peak at the beginning of the forward motion at themotor for the fixed flywheel mass can be reduced still further, if,after switching on the working cycle, the rotating loose flywheel massesare firstly coupled with the fixed flywheel masses by the frictionclutch and the latter are accelerated from the stationary position. Themotor for the fixed flywheel masses is switched on only after a certainperiod of acceleration.

It is expedient if there is provided a piston-andcylinder arrangementfor the displacement of the wedge. The transversely positioned spindlearrangement is advantageous for a cylinder-and-piston drive, in whichthe force effect expediently takes place on the wedge. During thedisplacement of the wedge in the direction of the spindle axis, thespindle and flywheel are caused to rotate via the spindle nut. In thecase of a hydraulic drive of this type, it is expedient to make thethread pitch of the spindle and spindle nut as large as possible. Thegreater the thread pitch, the smaller, however, the spindle rotationbecomes with predetermined ram velocity. For this reason, it is notpossible in conventional power presses to make the thread pitchsufficiently large, because with a reduction in rotation of the spindle,the flywheel masses had to increase by the square thereto. With theinterposition of a wedge drive and the higher spindle rotation connectedwith it, it is possible without any difficulty to make the pitch of thespindle thread sufficiently large.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is now described, by wayof example, with reference to the accompanying drawings, in which:

FIG. I shows, in section, a flywheel spindle press with an electricaldrive;

FIG. 2 shows, in section, a flywheel spindle press with a hydraulicdrive;

FIG. 3 shows, in section, a further hydraulic drive of a flywheelspindle press;

FIG. 4 shows, partially in section, a switchable slip clutch for aflywheel spindle press in accordance with FIGS. 1-3

FIG. 5 shows an electrical circuit for a flywheel spindle press inaccordance with FIG. 1 and a slip clutch in accordance with FIG. 4.

DETAILED DESCRIPTION OF THE EMBODIMENTS In the power press shown in FIG.1, a ram 2 is provided for guided reciprocating movement in a powerpress stand I, with the ram 2 carrying underneath it a tool 3. The pressstand I has at the top thereof a press head 4 which is provided with acavity 4a. In the cavity there is arranged a wedge 5 which slides withits longer, horizontally arranged cathetus on the top of the ram 2. Thehypotenuse 5a of the wedge 5 is adapted to slide on a sloping surface4/2 of the press head 4. When displaced sideways along the slopingsurface 412, the

wedge 5 rises and during the downward motion, it

presses the ram 2.downwards. It is possible to connect the wedge 5 tothe ram 2 in a sliding fashion so that when the wedge 5 is raised, italso raises the ram 2. However, it is expedient to provide a hydraulicpistonand-cylinder arrangement 6 which engages on one side onto the ram2 and on the other side onto the press head 4 to move the ram upwardsduring the return stroke.

A spindle 7 is disposed in two thrust bearings 8a, 8b on the press head4 and is axially immovable. A spindle nut 9 on the spindle 7 is axiallydisplaceable along the spindle 7 and engages onto the wedge 5. In thisway, the spindle end to be coupled with a drive does not effect anyaxial movement. The spindle nut 9 is provided on the wedge 5.

It is possible to arrange the spindle 7 horizontally and to have thespindle nut 9 engage vertically displaceably on the wedge 5 so that thespindle nut moves in a vertical direction with respect to the wedge andmoves together with the wedge in a horizontal direction. In the powerpress shown, however, the spindle 7 is provided with its axis arrangedparallel to the hypotenuse 5a of the wedge. In this way, the wedge 5 notonly abuts against the press head 4 but also against the spindle 7. Thespindle 7 passes through the wedge 5 and the spindle nut 9 as abovementioned is provided on the wedge At the lower end of the spindle 7there is arranged coaxially therewith, a flywheel 10 which isconnectable to the spindle by means of a switchable slip clutch 11. Anelectric motor 12 which is accommodated on the press head 4 serves asthe drive of the connectable flywheel I0. The upper end of the spindle 7is drivable by means of an electric motor 14 accommodated on the presshead 4. At the upper end of the spindle 7 there is also provided aconventional brake 13 which serves as brake during the return motion andas retaining brake. More particularly, the brake is provided in front ofan end piece 7a within a frame 14:! and this encloses the part of thespindle 7 projecting from the press head 4. The brake is a drum brake ofthe type known in the automobile field and checks 13h are provided onthe outside and a drum 13a on the inside. The drum is connected to thespindle. The motor [4 arranged at the upper end of the spindle is anelectric motor with a variable direction'of rotation. On the other hand,the electric motor 12 arranged on the opposite end of the spindle 7,runs in only one rotational direction.

The power press shown in FIG. 2 is to a large extent constructed in thesame manner as the power press shown in FIG. 1. However, in this case,the spindle nut 9a is arranged axially immovable in the press head 4a.The spindle 7a is shortened in comparison with the spindle 7 shown inFIG. 1, and is axially movable and engages with its lower end onto thewedge 5a but it does not pass thercthrough. It carries at its upper end,the flywheel which is not rigidly connected to the spindle and which canbe coupled to the spindle by means of the slip clutch 11a. The clutch11a is similar to and functions in the same manner as the clutch l1 andthe details thereof are illustrated in FIG. 4. It is possible to providea motor driving the connectable flywheel. A hydraulic piston andcylinder arrangement I5 is provided on the side of the press head 4aopposite the flywheel, the piston rod of which is connected to the wedge5a and which serves to displace the wedge not only to the right but alsoto the left with the displacement to the right causing a downwardmovement of the ram 2a.

A power press in accordance with FIG. 3 is likewise constructed to alarge extent in a manner similar to a press in accordance with FIG. I.What is different is that instead of a motor engaging at the spindle 7bin a non-releasable way, there are provided two piston-andcylinderarrangements 16 arranged on bothsides of the wedge 5b with the saidarrangements 16 serving to displace the wedge Sh. It is possible in thisembodiment to arrange that the contacting surfaces of the wedge and ramlie not horizontally but extend in a sloping manner, with the spindle 7hbeing arranged horizontally. Surfaces, which extend in a sloping manner,between the ram and wedge, however, have the disadvantage thatconsiderable forces come to bear on the ram guide, namely the horizontalpress force components against the respective surfaces. In thisembodiment, the flywheel 10b and slip clutch 11b are similar to theflywheel and slip clutch illustrated in FIGS. 1 and 4. The checks 1312are of the type shown on the brake 13 of FIG. I.

In the ideal-case, the slip clutch should be fully separated directly atthe beginning of the slipping. The impulse to separate can, however,only be given if the slipping has already begun, so that in practice theseparation takes place delayed in time with respect to the beginning ofthe slipping. One possiblity of triggering the separation of the slipclutch consists in that a contact finger mounted on the flywheel ispressed with spring force against a counter disc. The counter disc,which is connected to the spindle, possesses in the circular movementzone of the contact finger, a plurality of cam-shaped projections. Whenthe contact finger slides over these projections, the impulse forseparation arises. Another possibility of separating the slip clutchconsists in that the switch impulse is given electronically by frequencycomparison.

The switchable slip clutch shown in FIG. 4 is suitable for a power pressin accordance with FIG. 1. In accordance with FIG-4. an end piece I7 ofa spindle is guided in a cavity provided in a press 16 with the endpiece 17 rididly carrying a clutch disc 18 in the cavity. On the endpiece 17 a loose flywheel 19 is rotatably provided and which flywheelprojects from the cavity and carries an anchor disc 20 which is axiallydisplaceable but non-rotatable relative to the flywheel I9, and which isarranged parallel to the clutch disc 18. A friction lining 21 isprovided between the clutch disc 18 and the anchor disc 20. Disc rollers22 (of which one is shown) are provided between the two discs I8, 20 inchamber 24.

The loose flywheel I9 is driven via a shaft butt 23 by an electric motor12, which is secured, by means of a web 25, to the press stand 16'.Between the loose flywheel l9 and the anchor disc 20 compression springs26 are provided which are biased to press the anchor disc 20 against theclutch disc 18. On the anchor disc 20 there is accommodated an annularanchor 27 which embraces the loose flywheel I9 and is axiallydisplaceable thereon. If the anchor disc 20 is pushed back against thepressure of the compression springs 26, the annular anchor 27 is locatedinside a system of magnets 28, which is provided on the press stand 16.

When the clutch is released the disc can turn together with the looseflywheel 19 around the end piece 17 but it is also movable axially. Ifthe clutch is engaged, then the anchordisc is pressed with the lining 21against the clutch disc 18.

In the clutch disc 18 are provided recesses 18a into which part of therollers 22 project, with the rollers being adapted to rotate on shafts22a secured to the clutch disc 18. The part of each roller 22 oppositethe disc 18 projects into the chamber 24. The cross section of thechamber 24 tapers toward the right hand side of the disc 20 or, in otherwords, the chamber 24 is in the shape ofa trough. As soon as the anchordisc 20 rotates somewhat, the roller 22 rolls out of the chamber 24 andpresses the anchor disc towards the right (FIG. 4).

In accordance with FIG. 5, the system of magnets 27 is located via aswitch 29 on two voltage carrying leads 30a, 30b. The switch 29 can beactuated by means of a relay 29:: which can be connected to the voltagesupply via a switch 31 and/or a limit switch 32. The limit switch 32 is,in accordance with FIG. 1, provided on the press stand 1 in the vicinityof a cam 320 which is accommodated on the ram 2. The power press forwardmotion can be switched on by a switch 33, which is actuable by hand anda relay 31a is connected to the voltage supply, with the relay actuatingthe switch 31. Finally, there is provided a switch 34 via which a relay34a can be connected to the voltage supply and the return motion of thepress can be switched.

When the ram 2 travels downwards, then the forward motion switch 33 isclosed and the switch 31 and the limit switch 32 is opened so that theswitch 29 is opened and the system of magnets is not energized. Theanchor disc 20 is pressed by the compression springs 26 against theclutch disc 18. In good time before the lower dead point, i.e., beforethe ram 2 comes into contact with a work piece, the limit switch 32 isactuated so that the system of magnets 28 is energized. As soon theadjusted nominal moment of the slip clutch is attained during theforming of the work piece or in the ease of a rebound impact, therollers 22 are released from the chamber 24 and press the anchor 27 intothe system of magnets 28 so that the slip clutch is released. Since theanchor 27 is held firmly by the system of magnets 28, the clutch remainsreleased. If the return motion of the press ram 2 is switched on, theswitch 33 effecting the forward motion is opened so that the switch 31closes itself, by which the system of magnets 28 is energized during thewhole return motion and holds the slip clutch in the released state. If,then, it is again switched over to forward motion, i.e., the switch 33is closed, the switch 31 opens and, since the switch 32 is also opened,the system of magnets 28 becomes demagnetized so that the slip clutchcan engage under the action of the compression springs 26.

I claim:

I. A power forging press including a press stand provided with a drivehaving a flywheel, a threaded spindle and a drive device, a workpiecesupport, a ram mounted for relative movement with respect to saidworkpiece support, and a wedge housed in the press stand and acting onthe ram, said flywheel-spindle drive being arranged with the axis of theflywheel and its spindle extending transversely to the direction ofmovement of the ram, and means operably connecting the spindle andwedge.

2. The power press as claimed in claim 1 in which at least said ram ismounted for vertical movement toward and away from the workpiecesupport.

3. The power press as claimed in claim 1 in which said ram is mounted inthe press stand above the workpiece support for vertical movement towardand away from the workpiece support.

4. A power forging press provided with a press head, and a drive havinga flywheel, a threaded spindle and a drive device, an anvil, a ramarranged above the anvil adapted to move upwardly and downwardly anddevices for raising the downwardly pressed ram upwardly,

the improvement being the flywheel spindle drive is arram and wedge arevertically displaceable and displaceable relative to each other and inwhich a piston-andcylinder arrangement defines the devices for raisingthe ram upwardly, said piston-and-cylinder arrangement being engaged onone side thereof to the ram, and on the other side thereof, to the presshead.

7. The power press as claimed in claim 4 in which the spindle isimmovable in an axial direction.

8. The power press as claimed in claim 4 in which the wedge has ahypotenuse and the spindle is arranged with its axis parallel to thehypotenuse of the wedge.

9. The power press as claimed in claim 4 in which the flywheel can becoupled to the spindle at one end and in which drive means for thespindle is provided at the other end thereof.

10. The power press as claimed in claim 4 in which a piston-and-cylinderarrangement is provided for the displacement of the wedge.

1. A power forging press including a press stand provided with a drivehaving a flywheel, a threaded spindle and a drive device, a workpiecesupport, a ram mounted for relative movement with respect to saidworkpiece support, and a wedge housed in the press stand and acting onthe ram, said flywheel-spindle drive being arranged with the axis of theflywheel and its spindle extending transversely to the direction ofmovement of the ram, and means operably connecting the spindle andwedge.
 2. The power press as claimed in claim 1 in which at least saidram is mounted for vertical movement toward and away from the workpiecesupport.
 3. The power press as claimed in claim 1 in which said ram ismounted in the press stand above the workpiece support for verticalmovement toward and away from the workpiece support.
 4. A power forgingpress provided with a press head, and a drive having a flywheel, athreaded spindle and a drive device, an anvil, a ram arranged above theanvil adapted to move upwardly and downwardly and devices for raisingthe downwardly pressed ram upwardly, the improvement being the flywheelspindle drive is arranged with the axis of the flywheel and spindlerunning transversely to the direction of movement of the ram andactuating a wedge housed in the press head above the ram acting on theram.
 5. The power press as claimed in claim 4 in which the wedge isprovided with a horizontal cathetus and a hypotenuse, with thehorizontal cathetus gliding above on the ram and the spindle having anaxis arranged in parallelism to the hypotenuse of the wedge.
 6. Thepower press as claimed in claim 4 in which the ram and wedge arevertically displaceable and displaceable relative to each other and inwhich a piston-and-cylinder arrangement defines the devices for raisingthe ram upwardly, said piston-and-cylinder arrangement being engaged onone side thereof to the ram, and on the other side thereof, to the presshead.
 7. The power press as claimed in claim 4 in which the spindle isimmovable in an axial direction.
 8. The power press as claimed in claim4 in which the wedge has a hypotenuse and the spindle is arranged withits axis parallel to the hypotenuse of the wedge.
 9. The power press asclaimed in claim 4 in which the flywheel can be coupled to the spindleat one end and in which drive means for the spindle is provided at theother end thereof.
 10. The power press as claimed in claim 4 in which apiston-and-cylinder arrangement is provided for the displacement of thewedge.